Automatic safety device for pneumatic hammers



June 29 1926.

2 Sheets- Sheet l C. B. WADE AuToMATc sxggfngnc Fon PNEUMATIG HAramBRs'Y -ys/a.

.lu-ne 29 1926.

C. B. WADE AUTOMATIC SAFETY D-EVICE FOR PNEUMATIC HAMMERS Filed March22, 1924 2 Sheets-Sheet 2 which controls the inlet Patented June 29,1926.

unirse stares insane Partnr trice.

CHARLES B. VJ'ADEV, OF'ROANGKE, VIRGINA.

Application filed March 22, 1924. Serial No. 701,159.y

My inventiourelates to a safety device used on pneumatic hammers of anydescription such as riveting, calking and chiseling hammers, and thelike.

In hammers of this class, the bit inserted at the operating end of thehammer fits loosely therein so that in case the pressure on the bit ismomentarily released While the trigger is still held to admit pressurefluid into the hammer, it often happens that the bit is thrown outviolently from the hammer, thereby causing serious accidents.

The main object of the present invention is to furnish an automaticsafety device which closes the inlet port for the pressure fluid intothe pressure chamber of the hammer immediately the bit is moved awayfrom the Work independently of whether the trigger actuating' thethrottle for admitting pressure fluid into the hammer is released ornot. Accordingly, the plunger Vin the hammer will immediately be stoppedagainst the bit so that the latter cannot fly out from its seat. p

ln some pneumatic hammers of late lconstruction an operating rod isfurnished abutting the collar on the bit at one end and at the oppositeend in Contact with a valve sure chan'iber. This valve is installed inaxial alinement with the operating rod with the consequence that thepressure fluid *.vill act directly on the contacting end thereof andpush the rod hard against the bit, and the operator will have toovercome this additional pressure when he applies the hammer against thework.

This disadvantage is entirely removed from the safety device forming thesubject matter of the presentY invention, so that the operator does vnothave to use more force than with an ordinary pneumatic hammer Withoutsuch safety device.

In the accompanying drawings,V Figure l is a fragmentary side elevationand partial With a preferred axial section'of the hammer construction ofthe safety device; Figure 2 is a side elevation section of some of thedetails;

Figure 3 is a top plan of the safety device:

Figure 41s a bottom same;

and not driven port in the air pi'esand partial view of the casing orvalve block containing the main parts.

plan view of the f Figure 5 is a vertical section along line 5&5 of Fig.3;

Figure 6 vis a similar section along line 6-5 of Fig. 3; i

Figure' is a sidey for saidcasing.

Figure 8 is al fragmentary vertical section of the hammer with aslightly modified form of safety device; f

Figure Sis a top plan view, corresponding to Fig. 8, of the casing usedin the modified form shown in Fig. 8, and u Figure l0 is a fragmentarysectional view of the upper end of the liaminershowing still anothermodification. Y V

Fig. 1l is a detail section on the' line ll-ll of Fig. l.

ln the drawings, Vreference ruimer-al represents the cylinder of apneumatic hammer and 16 is a bit vmounted in the usual manner in thelower end of the cylinder l5 and retained therein by a clipV 17permitting a slight reciprocatio-n of the bitin relation to thecylinder. The upperend of the cylinderl is threaded as at 18 in yorderto receive a head 19. This head is provided with a conventional handle2O in which a fluid pressure passage 2ll containing the usual throttlewith 'a groove or port 23 opening through the flat roof 2st of the' headVinto the Working cylindrical pressure chamber of the hammer. lu theupperend of the cylinder is the usual sleeve 26 which tstightly on theshoulder 2'? ink thepressure chamber and houses the plunger, thepressure fluid. exhausting from the sleeve in the usual manner. ln or erto accurately seat the sleeve in the cylinder l5 and prevent it fromturning. the lower end ofthe sleeve is provided With a-dowel 28 adaptedto engage a corresponding .recess shoulder 27 of the cylinder. The upperend of the sleeve' is similarly 'provided with dow'els 30,' thefunctioning of which will be described later. The construction thus fardescribed is Well-known andconstitutesV no part o-f my presentinvention'. i

elevation of a bushing l'Along one side of the cylinder l5 is guide 3lextending the' formedv a tubular I entire length thereof and opening atits loivei-,end above a collar valve' connects a supply hose 22.

29 furnished in theV n 32 onthev-bit 16.`` Above the shoulder 27 theguide is conl tinu'ed half ofit, as at 38, being furnished in the sideof the sleeve 26, see particularly Fig. 2. The upper end of this guideis enlarged, as at 34, toaecommodatemthe on the lact-uating-rod '36jwhiei'i v sf'slidfably in the guide with its extreme loive'fr endrestingupon the collaiI 32 of the bit`16,.

As indicated'in Fig. 4{yt-lie upp'erfend `-of the cylinder 1.5 continuesabovethe top end of the sleeve 26, and kinthe end f tl'ie"cyl-` inderbetween the endof thepsleeve.,andthe roof 24 of the head 19 is inserteda 4cylindricalj'plugyor valve block withflat top and the bottom side.offwhieh is is closed by a cap 42 preferably threadedin to thefvalveblock against Concentric with the bore 40 are yemlnterbores `or annular44 the former of 'which is positioned centrally therein, that 'iis' toVsay, substantially in theaXial-,plane of the valve block and thecylinder 15. The'. other-groove isvadj acent tliejopen end of the bore.tersecting at right ga1-1g-le's' `withtheI bore 40 is drilled `atransversepaseage 545i-fthe open bushing. provided two grooves 4.3 and:endsv of'which-are -close'dby l'tight fitting plugs 4,6. From thistransverse-rpassageextendfupwardlyto :the top "facenof the housing 3?,two ports47 adapted to register with theportsV 23 itheghammerhead '19..In the bottom Y fae'ef'48 ofthe 'valve block 37 "iscut an annularfgroove49,- the outer diameter of which' "is substantially the sanefas theldistance between the outer@ walls Aof-.the ports 47 Yin the top of the`block. tablish communie ation `between this annular groove 49 and thetransverse bore 40 Ea passage 50 is pr'ovided between the two, seesparticularly gigs. 4V and f6. :Thei enlarged porblock 37, half; ofthislextension 522being1cut in the valve-block'and'the otherhalf intheDepending "on: the length ofV cylinder-*15. the bushing I41the innemend-of the -latter will also? be eut out, as'at"`53,'1infFig., in head 35l.-'ofv vtheactuating"rod order y thatthe 36 will be ableto'freely"reciprocate in the guide. Inorder to'faeilitate manufacture,

through theytop ofgefthevalve blovelzSLf/as seen inFigs L 2`1and: "3 and'thegpenendpf had 35,

'In `forder to eswall thereof and the valve block 37. The

reason'for furnishing this plug 54 is to provide an abutmentlfortheupperend of the lieadf' ofthe actuating rod'to limit its upwardmovement. y

VIn the bushing 41 is mounted to recipro- `-cate yav'alve plunger `55between which and theL cap 42 `is inserted a compression spring"56,'s"e`eFig."l. 'This plunger has a head 5T,

neek 58:-.and5pabase 59, all integral parts. A seat is furnished in thebushing 4l forthe tapered end of 'the-base L59 ofthe valve-plunger-.This forms a tight `joint when the 4valve plug -is pressed into'the seatby the spring 56,V thus vpreventing all leakage forward ofthe base, thatis to say,from the inlet ports 63 to the outlet ports 64. In'y ordergtotake care of fany leakage tothe :rear ofthe -valvephuiger :and lpermitescape of air -whieh would otherwisehe compressed -by the openingmovement of 'the val-vez and preventy itsfcomplete opening, a small airventor exhaust passage 74 .is provided in the cap 142.and continuedthrough thewalls of the cylinder v15 and the head 19. The head has-'atapered nose 60adapted-toregister with fthe correspondingly beveledupper 'end ofuthe lactuating krod head 35, as Ibest 'seen in Fig.

- The bushing -41 isi-provided with vtwo exter-vnalfannular grooves 61and 62, shown most ole'arlyfin Fig. 7, which register Vwith theannularfgrooves 48 and A44 ,respectively int the valve-block..Communicating withi'the interior of the bushing 41 are radial ports y63 "andf 264m :the grooves 6lrk :and 62 respectively formed, 'throughthe wall off the bushing *41. A'lhesrelative :positions of 'these portsare such that vwhen'the yplungervalve .55 fis iny a clos'ed fposition,as indicated-in Fig.jl-,-thegports 63 will be closed by the base 59""ofthe plunger -while theuports k64 remain constantly open 'whetherthevalve is in forn ward or retracted position.-

The operation of the device' is as follower f During"transportation"orwhen f the hainmer is Anot :in 1"actual use, the f position vof theparts is as shown in l, that-is teeny" vthe'jbiti"lr'is infits'outerm'ostf position land the actuat1ng1rod36 rests vrwith.' itsI'lower end against `Vtheieollar 32. i This iseau'sed" by the pressurey'of the'spring '56I against' the plunger valve '55wherebyfzthebevelnose 60eonipels the bevel head tomove downwardly. `=It willY beevident'fthat even if the trigger 65 be preseedYdown-to 'lopen thethrottle. valve in "the l' passage" 21', "therebyf admitting f pressurefluid intoithe" Orts 23, this-pressure fluid canfrpass 'no ffurther-becausel the 59 of the )valve :plu'nger''eloses fup'onf the se at"175': and 'across Ath'e ports VT68, in 4lthe' bush- `upper Vbeveled endof the rod will ni'ove groove 49 in the valve block, whence it enters'the sleeve 26 to actuate the hammer plunger or piston in the usualmanner.

In Figs. 8 and 9 is shown a modiicat-ion consisting in providing acentral. aperture 66 in the valve block 67 instead ot the two side portsAi?, although obviously al three ports may be used if desired. loregister with this central aperture 66, a corresponding aperture 68 isprovided in the head 69 Communicating with the fluid pressure passage 70in the latter. he operation et this inodilied device is identical withthat ot the preferred form of the device, the only di't terence beingthat the pressure Huid enters centrally into the. bushing 7l.

ln File". l0 is shown still another modification ditl'ering from the twoforms already described only by providing a valve block 7 2 of adiameter corresponding to the threads 18 on the cylinder l5. ln thiscase the hammer head 19 may be built slightly longer so that the block72 rests` as before, on top ot the sleeve 26 which projects slightlyabove the threaded end ot the body cyl inder l5, as indicated in thisfigure.

The main reason for furnishing a bushing is to facilitate repairs as thebushing` is eX- posed to constant wear and it is evident that, dependingupon the material used tor the valve block, the valve plunger 55 may beinserted directly into a bore furnished in the block without theii'itermediary of a bushing.

It is also evident that in some cases the head 19 itself may beconstructed to receive the valve plunger 55 although such constructionwould somewhat increase the cost oi manu-facture and prevent easyreplacement of parts. As shown in the drawings, it will be clearlyunderstood that this safety device can be applied very easily toexisting hammers all the parts needed for the same are included in thevalve block 37 with the exception ot the actuating rod 36 for which theguide 31 would have to be drilled in the hammer body.

The term bit in the specification and claims is intended to include anyhind of punch, rivet set, chisel or other specific tool operated by apneumatic hammer.

From the above description and the showing` of the accompanying drawingsit will be evident that this device has still another advantage, namely,that it is immaterial in what angular position the head engages thethreaded upper end of the c},flinder, because the valve block 37 iskeyed in the chamber 25 through the intermediary ot the sleeve 26, whichwill always cause the guide poi tion 52 in the block to register withthe corresponding guide portion in 'the cylinder l5.

Having thus described the invention, what is claimed as new isi Y l.rlhe, combinationv with a pneumatic hammer includingI a c flinder, a bitmounted in one end oi the cylinder and a handle at the opposite end ofthe cylinder having a passage for conveying pressure fluid to 'thecylinder, of a controlling` valve inounted transversely to the cylinderbetween the saine and the handle, yieldable means holding thecontrolling valve norn'ially in. closed position to cut oit flow oipressure fluid to the cylinder, and a slidable actuating rod mountedlongitudinally in the cylinder with i one end in contact with but freeof the bit and its opposite end bearing freely against the end of thecontrolling valve in opposition to said yieldable means whereby to opensaid controlling valve when the bit is pressed against the work.

2. The combination with a pneumatic hammer including a cylinder, a bitmounted in one end of the cylinder, and a handle at the opposite end ofthe cylinder having a passage for conveying pressure fluid to thecylinder, of a plunger valve mounted slidably across one end of thecylinder between the saine and the handle, an expansion spring bearingagainst one end of said valve to hold the valve normally in closedposition cutting Voti flow ot pressure fluid, and a slidable actuatingrod mounted longi tudinally in the wall of the cylinder with one endbearing upon the end oi' the plunger valvey remote trom the spring andacting in opposition to the spring and its opposite end in contact withthe bit whereby to open said .valve when the bit is pressed againstwork,

3. The combination with a pneumatic hammer including a cylinder, a bitmounted in one end of the cylinder, and a handle at the opposite end otthe cylinder having a passage for conveying pressure fluid tc theycylinder, ot a plunger valve mounted slidably across one end of thecylinder between the same and the handle, an expansion spring` bearingagainst one end of said valve to hold the valve normally in closedposition cutting oilC flow of pressure fluid, the opposite end of saidvalve being beveled and a slidable actuatingl rod mounted longiftudinally in the wall of the cylinder with one end beveled and bearingupon the beveled end of the plunger valve and acting in opposition tosaid spring and its opposite end in contact with the bit whereby to opensaid valve when the bit is pressed aga-inst work.

et. The combination with a pneumatic los llt)

CAB

hammer' including a cylinder, -a ybit mounted in one end ofthe cylinder,a handle at the opposite end Aof the cylinder having a passage 'forconveyingpressure liuid to the cylinder` and a sleeve in the cylinder,el`

a Valve block held lixedly in the end of the cylinder byand between thehandle and the sleeve, a eontrolling valve mounted slidaloly in thevalve blocl transversely to the cylinder, yieldable means housed intheValve bloel: and acting onv said valve to hold it normally closed to Cutolil flow of pressure luid, and an actuating rod mount-ed'slidablylongitudinally between the Walls o'l` the cylinder and the sleeve withone end vbearing upon the Controlling Valve in opposition to saidyieldable means and its opposite en( in Contact with the bit whereby toopen said Valve When the bit is pressed against work.

5. The Con'ibination With a pneumatic hammer including a cylinder, abitmount ed in one end of the cylinder, handle at the opposite end of thecylinder having' a passage for conveying pressure 'fluid to thecylinder, and a sleeve in the cylinder, ol a valve block held in theVend oi i'heioylinder by and between the handle and the sleeve andhaving inlet, doWels on the ends of the sleeve engaging in apertures inthe body of the cylinder and in the lower side oil-the valve bloel;respectively whereby to los; VJthe valve block against turning. aeontrollinrr Valve mounted*` slidably in the valve bloei( transverselyto the Cylinder, yieldable means housed in the valve bloek and acting onsaid valve to vhold it normally olosedto ,out od flow of pressure fluid,and an actuating rod slidably mounted longitudinally between the Wallsof the cylinder and the sleeve with one end bearing upon the controllingvalve in opposition'to the yieldable means and its V opposite end inContact with the bit whereby to open said Valve when vthe bit is pressedagainst work.

.6. lThe combination with a pneumatic hammer including a cylinder, a bitmou-nted in one end of the cylinder, and a handle at the opposite end ofthe cylinder having a passage lior conveying` pressure fluid to thecylinder, ot' a slidable Controlling valve mounted transversely to thecylinder Ybetween the sameV and the handle, yieldable means acting uponone endolz said valve to hold the saine normally in closed positioncutting' ofi llow of pressure fluid to the oylinder,` and means `mountedupon the Cylinder operatively enffaged rwith the bit :and said yalye andacting upon said valve in opposition to said yieldable i'neans wherebyyto open the vvalve when the bit .is `pressed against Work.

7. The combination with a pneumatic hammer including a cylinder, a bitmounted in one end of the cylinder, and aihandle secured on the oppositeend of 'the-cylinder and having apassage for conveying pressure lluid tothe cylinder, of a Valve block secured in the dast-mentioned .end not`the cylinder :against 'the `handle and provided with ports in its topcommunicating with the passage ir the handle ,an outlet inthe bottom ot'the Val-ve vblock for discharging lluid into lhe cylinder, and adiametriea'l bore in eonnnunieation with said ports and sae outlet., ayalveslic'lahly mounted usaid bore andhavingv a tapered head at oneend,yieldable means for holdingthe :valve lnormally ao-ross the ports in-the.atop 'of 'the Valve hloel with its'tapered f,head projectingthroughythe side of the block, and a roc slidably mounted in the -Wall of thecylinder With one end resting, against the vbit and its opposite' endtapered 4and resting upon the tapered head-of the Valve whereby -to.aotuate the valve in opposition to the yieldable means when' the bit ispressed to its work.

In testimony Whereolaliix my signature.

CHARLES n. wenn. [ns- 1

